Levent Gizem, Anderson Robin C, Petrujkić Branko, Poole Toni L, He Haiqi, Genovese Kenneth J, Hume Michael E, Beier Ross C, Harvey Roger B, Nisbet David J
United States Department of Agriculture, Agricultural Research Service, Food and Feed Safety Research Unit, College Station, TX 77845, USA.
Department of Veterinary Pathobiology, Texas A&M University, College Station, TX 77840, USA.
Microorganisms. 2021 Apr 16;9(4):860. doi: 10.3390/microorganisms9040860.
The gut of food-producing animals is a reservoir for foodborne pathogens. Thymol is bactericidal against foodborne pathogens but rapid absorption of thymol from the proximal gut precludes the delivery of effective concentrations to the lower gut where pathogens mainly colonize. Thymol-β-d-glucopyranoside is reported to be more resistant to absorption than thymol in everted jejunal segments and could potentially function as a prebiotic by resisting degradation and absorption in the proximal gut but being hydrolysable by microbial β-glycosidase in the distal gut. Previous in vitro studies showed bactericidal effects of thymol-β-d-glucopyranoside against , , and serovar Typhimurium in the presence but not absence of intestinal microbes expressing β-glycosidase activity, indicating that hydrolysis was required to obtain antimicrobial activity. Presently, the oral administration of thymol-β-d-glucopyranoside was studied to examine the effects on intestinal carriage of , , and Typhimurium in swine. The effects of thymol-β-d-glucopyranoside or thymol on antimicrobial sensitivity of representative isolates and characterized strains were also explored. Results from two in vivo studies revealed little antimicrobial effects of thymol-β-d-glucopyranoside on , , or Typhimurium in swine gut. These findings add credence to current thinking that hydrolysis and absorption of thymol-β-d-glucopyranoside and thymol may be sufficiently rapid within the proximal gut to preclude delivery to the distal gut. Antibiotic susceptibilities of selected bacterial isolates and strains were mainly unaffected by thymol. Further research is warranted to overcome obstacles, preventing the delivery of efficacious amounts of thymol-β-d-glucopyranoside to the lower gut.
食用动物的肠道是食源性病原体的储存库。百里香酚对食源性病原体具有杀菌作用，但百里香酚从近端肠道的快速吸收阻碍了有效浓度的药物传递到病原体主要定植的远端肠道。据报道，在空肠翻转段中，百里香酚-β-D-吡喃葡萄糖苷比百里香酚更不易被吸收，并且它有可能作为一种益生元发挥作用，即在近端肠道中抵抗降解和吸收，但在远端肠道中可被微生物β-糖苷酶水解。先前的体外研究表明，在存在而非不存在表达β-糖苷酶活性的肠道微生物的情况下，百里香酚-β-D-吡喃葡萄糖苷对肠炎沙门氏菌、鼠伤寒沙门氏菌和猪霍乱沙门氏菌具有杀菌作用，这表明需要水解才能获得抗菌活性。目前，对猪口服百里香酚-β-D-吡喃葡萄糖苷进行了研究，以检验其对猪肠道中肠炎沙门氏菌、鼠伤寒沙门氏菌和猪霍乱沙门氏菌携带情况的影响。还探讨了百里香酚-β-D-吡喃葡萄糖苷或百里香酚对代表性沙门氏菌分离株和特征性菌株抗菌敏感性的影响。两项体内研究的结果显示，百里香酚-β-D-吡喃葡萄糖苷对猪肠道中的肠炎沙门氏菌、鼠伤寒沙门氏菌或猪霍乱沙门氏菌几乎没有抗菌作用。这些发现支持了目前的观点，即百里香酚-β-D-吡喃葡萄糖苷和百里香酚在近端肠道内的水解和吸收可能足够快，从而无法将其传递到远端肠道。所选细菌分离株和菌株的抗生素敏感性主要不受百里香酚的影响。有必要进行进一步研究以克服障碍，从而防止将有效量的百里香酚-β-D-吡喃葡萄糖苷传递到远端肠道。
